Srs2 prevents abscission-dependent DNA damage following replication stress. (A) Abscission is scored by measuring the distribution of GFP-CAAX intensity values across the mother–daughter cell axis at the bud neck. Upper panel: Cells that have yet to abscise show a single peak of intensity at the bud neck. Lower panel: Membrane separation is marked by two distinct peaks in GFP intensity. (B) Membrane ingression and abscission in WT and srs2∆ cells with or without an HU pulse. Cells express the plasma membrane marker CAAX-GFP and the spindle pole marker Spc42-GFP (yellow arrows). Time is indicated in minutes; 0 min indicates the start of membrane ingression. Asterisk specifies membrane ingression. White arrowhead marks complete constriction of the plasma membrane (abscission). Single Z-slices are shown, but 12 Z-slices spaced 0.3 μm, spanning the whole cell, were used for image analysis. (C) Fraction of cells that complete abscission from the time of membrane ingression. n = number of cells pooled from N = 3 independent experiments with similar results. WT vs. WT +HU, and WT +HU vs. srs2∆ +HU, P < 0.0001, Mann–Whitney test. (D) Frequency of Mre11-GFP focus formation after cytokinesis in the indicated strains and conditions. The P values correspond to Fisher’s exact test. Representative images of cells expressing Mre11-GFP, after cytokinesis following a HU pulse. The arrow points to a nuclear Mre11 focus. Scale bars in A, B, and D: 5 μm.